Finally finished this! Took about 45 hours, but it was worth it.
Mid-way through the drawing I bought some new supplies - two 0.3 mm mechanical pencils, and a thin eraser for details. I filled one mechanical pencil with B lead, the other with H lead. They were an absolute necessity in drawing something like this that demanded clean, sharp lines. I also switched from a Faber-Castell set to Tombow Monos. A slight upgrade.